Truncate trace_id for specific LightStep requirements

Author: ocelotl

lightstep/tracer.py

@@ -82,6 +82,47 @@ def __init__(self, enable_binary_format, recorder, scope_manager):
             self.register_propagator(Format.BINARY, BinaryPropagator())
             self.register_propagator(LightStepFormat.LIGHTSTEP_BINARY, LightStepBinaryPropagator())
 
+    def start_active_span(
+        self,
+        operation_name,
+        child_of=None,
+        references=None,
+        tags=None,
+        start_time=None,
+        ignore_active_span=False,
+        finish_on_close=True
+    ):
+
+        scope = super(_LightstepTracer, self).start_active_span(
+            operation_name,
+            child_of=child_of,
+            references=references,
+            tags=tags,
+            start_time=start_time,
+            ignore_active_span=ignore_active_span,
+            finish_on_close=finish_on_close
+        )
+
+        class ScopePatch(scope.__class__):
+
+            def __exit__(self, exc_type, exc_val, exc_tb):
+
+                self.span.context.trace_id = int(
+                    format(self.span.context.trace_id, "032x")[:16], 16
+                )
+
+                result = super(self.__class__, self).__exit__(
+                    exc_type, exc_val, exc_tb
+                )
+
+                return result
+
+        # This monkey patching is done because LightStep requires for the
+        # trace_id to be 64b long.
+        scope.__class__ = ScopePatch
+
+        return scope
+
     def flush(self):
         """Force a flush of buffered Span data to the LightStep collector."""
         self.recorder.flush()

tests/trace-context/trace_context_test_service.py

@@ -47,10 +47,6 @@ def hello():
                 timeout=5.0,
             )
 
-            scope.span.context.trace_id = int(
-                format(scope.span.context.trace_id, "032x")[:16], 16
-            )
-
     return 'Hello, {}!'.format(hello_to)